1. Technical Field
The present invention relates in general to data processing or information handling systems and, in particular, to a method and system for fetching data from memory. Still more particularly, the present invention relates to a method and system for pre-fetching data from memory based upon a pre-fetch history table.
2. Description of the Related Art
As processor clock frequencies have continued to increase, thereby permitting increased instruction throughput, memory latency has become a principal impediment to improved processor performance. Although instructions are commonly speculatively fetched from memory in order to ameliorate the effects of instruction access latency, in a conventional processor data is fetched from memory only after a load instruction has been executed to determine the address of the data to be fetched (i.e., only demand fetching is used).
The present invention includes a recognition that in order to reduce data access latency, it is desirable to intelligently pre-fetch data from memory. Modern microprocessors employ pre-fetching in order to reduce the latency involved in cache misses. An improved pre-fetching mechanism is needed to more accurately determine that a pre-fetch is likely to be useful as well as the best target to pre-fetch. The subject invention herein solves this problem in a new and unique manner that has not been part of the art previously.